Two beams of protons circulate around the 27km circumference of the Large Hadron Collider tunnel under the Franco-Swiss border. Those protons moving clockwise collide, head on, with those moving anticlockwise and the collisions take place in the middle of cavernous detectors. The scientists working on two of these detectors have made it their immediate priority to find the much vaunted Higgs particle and, towards the end of last year, the first, tentative, evidence of the particle's existence was made public. Next month, at an international conference in Australia, we can expect to hear the latest news on the hunt. The burning question is whether, with more data, the experimental evidence will strengthen or weaken. So what is the evidence and why do we need to keep waiting on tenterhooks?

When two protons crash into each other they break up, producing hundreds more particles that spray out in all directions, like an exploding firework. The huge detectors are designed to capture the debris and provide a snapshot of the collision.

The challenge for physicists such as me is to make sense of these snapshots. Complications arise, however, because we do not know what is going to happen in any single collision; we can only use our theories to predict the odds on any particular thing happening. The collisions occur at a ferocious rate (almost 1bn every second), but even then we can expect to wait upwards of an hour for a single Higgs particle to produce a distinctive pattern in the detectors.

The trouble is that the pattern is not distinctive enough – the detectors do not light up and proclaim the arrival of a Higgs particle. Instead, we have to deal with the fact that those multitudinous Higgs-free collisions can also lead to a pattern in the detectors that looks just like a Higgs collision and those fakes are likely to outnumber the real thing by a factor of 20. At first sight, the situation seems hopeless, but time is on our side.

Imagine tossing a coin five times. You would not be very surprised to get four heads but, after tossing the coin 500 times you would be right to say it is biased if it came up heads 400 times. This is an example of a general rule in statistics: the randomness associated with averaging over a small number of events tends to cancel out when we average over bigger samples.

In the hunt for the Higgs, we can benefit from this statistical effect by performing a sufficiently large number of collisions because, if the Higgs particle exists, it becomes increasingly unlikely that sightings of the Higgs-like pattern can be ascribed to the non-Higgs fakes. The Cern scientists are able to put a number on just how unlikely it is that the fakes alone can account for the data. When that number gets small enough, they will then issue a statement along these lines: "We are seeing patterns in our detector that look like they were made by a Higgs particle and which occur too frequently for them to be explained by the no-Higgs hypothesis… specifically, the probability that the no-Higgs hypothesis can explain our data is smaller than 0.00003%."

That number is chosen because it is so small that any reasonable person would be convinced that, in all likelihood, something interesting is happening (it is, roughly, the odds of an unbiased coin coming up heads 20 times in a row). This is why discovering the Higgs particle is a waiting game. Fortunately, with collisions occurring at the dazzling rate of 1bn proton collisions every second, the finishing line is now in sight.

The Cern scientists are going to put a number on the likelihood that a theory can (or cannot) explain their data and, in a sense, that is all they will do. They will not be making definitive statements – they will be quoting the odds. This is not something peculiar to particle physics at the LHC – it is the bottom line in science. Good experiments allow us to conclude that somebody's theory about this or that is unlikely to be correct and the good theories are those that survive, at least until the next experiment.

Good theories are also able to predict new things – things that can be tested in new experiments. Those theories that survive this repeated and unsentimental attempt to test them to destruction are, as a result, supported by what can become a mountain of evidence. This is what it means to know something in science. This is knowledge that is not so much concerned with the quintessential nature of reality; rather, it is knowledge built on direct experience. It is practical knowledge that works.

If there is one thing that being a scientist has taught me, it is how difficult it is to know something with certainty. Without the anchor of experiment, it is very easy to become seduced by an idea and develop the impression of understanding where none really exists. Doing real science is a humbling experience. It is commonplace to find that an elegant theory fails to describe the data and, in the words of American physicist Richard Feynman, it doesn't matter how beautiful your theory is, how smart you are or what your name is – if it doesn't agree with the data then it is wrong.

Getting things wrong is part of good science and it makes it all the more rewarding when theory and experiment do finally agree with each other.